Michigan Supreme Court Vacates Line 5 Pipeline Replacement Approval
Michigan Supreme Court vacated approval of Enbridge's Line 5 pipeline replacement project.
Why it matters: Court rulings on environmental compliance can delay major energy infrastructure projects and shape regulatory scrutiny. Legal and regulatory professionals should anticipate increased judicial involvement in environmental reviews.
- Michigan Supreme Court vacated the Michigan Public Service Commission's December 2022 approval of Enbridge's Line 5 replacement on August 3, 2023.
- The court required regulators to conduct a comprehensive environmental impact assessment including alternatives evaluation.
- Enbridge's proposal replaces dual 20-inch pipelines with a single 30-inch pipeline inside a concrete-lined tunnel beneath the Straits of Mackinac.
- Line 5 transports up to 540,000 barrels per day and has a history of safety incidents, including a 2010 oil spill and a 2018 anchor strike.
On August 3, 2023, the Michigan Supreme Court vacated the Michigan Public Service Commission's (MPSC) December 2022 approval of Enbridge Energy's Line 5 pipeline replacement project beneath the Straits of Mackinac. This ruling temporarily halts the $500 million plan pending a new environmental review.
Enbridge’s project envisions removing two existing 20-inch pipelines built in 1953 and installing a single 30-inch pipeline inside a concrete-lined tunnel under the Straits. The Line 5 pipeline carries up to 540,000 barrels of light crude oil and natural gas liquids daily from Superior, Wisconsin, to Sarnia, Ontario.
The court concluded that MPSC’s environmental assessment was inadequate because it failed to evaluate alternative pipeline configurations and environmental impacts comprehensively. The ruling demands regulators conduct a thorough environmental impact assessment, emphasizing alternatives analysis. You can read the full opinion here.
Line 5 has experienced previous safety and environmental issues. In 2010, it suffered a spill releasing approximately 21,000 barrels of heavy crude into a Kalamazoo River tributary. Further, a 2018 anchor strike damaged the pipeline in the Straits, raising ongoing concerns about its structural integrity.
Environmental and tribal leaders voiced strong opposition. Whitney Gravelle, President of the Bay Mills Indian Community, stated in an official press release that the pipeline and replacement plan threaten "our clean water, our fishing, and our way of life." Similarly, Beth Wallace from the National Wildlife Federation criticized state leadership, accusing Governor Whitmer of contradictory actions on pipeline regulation.
This ruling underscores increasing judicial scrutiny of environmental compliance in energy infrastructure projects. It signals legal professionals and regulators to expect more detailed and rigorous environmental reviews, particularly for projects involving sensitive ecosystems and public trust resources.
By the numbers:
- 540,000 barrels per day — capacity of Line 5 pipeline under the Straits of Mackinac
- 21,000 barrels — amount of heavy crude spilled in 2010 Kalamazoo River incident
- $500 million — estimated cost of the Line 5 pipeline replacement project
What's next: The Michigan Public Service Commission must issue a new environmental impact assessment that addresses the court’s concerns before the pipeline replacement project can proceed.